Bit



June 4, 1957 s. A. STOKES 2,794,623

BIT

Original Filed May 23, 1947 s Sheets-Sheet 1 r ,22 I r I0 i H v 3 3 23 I Z2 J INVEN TOR. STANLEY ARCHER STOKES AT TORIV Y June 4, 1957 s, STOKES 2,794,623

BIT

5 Sheets-Sheet 2 Original Filed May 23, 1947 9 a7 asJ I: v INVENTOR. ii= 52' STANLEY ARCHER 510x53 BY 22M ATTORNEY S. A. STOKES June 4, 1957 BIT 3 Sheets-Sheet 5 Original Filed May 23, 1947 FIGJI.

Bla.

ATTORNEY United States Patent nrr 9 'Glaims. (Q1; 255-89) This invention relates to drill bits and provides improved 'drill bits ofnovel design particularly applicable 1 to drilling holes in concrete, stone and similar hard, abrasive materials. The present application is' a division of -my (Ed-pending application Serial No. 749,941 filed May 23, .1947, entitled Bits and issued" September 4, 1951, asZUnitd -'S'tates"Patent 2,567,084 and constituting acontiuuation-in=part of myithe'n co=pending application Serial "No; 71-2.,770;filed?November 29; 1946', entitled Bits and issued-August ;I947,'as United States" Patent 2,425,132. .The .drilhbit 'as;des,cribed in myaforementionedTPatent 2,425,132 is designed to operate by grinding action as wabble or oscillate slightly, and this action aids the rodistinguish'ed from-a cutting action' 'an'd ini'essence'c'om- -.--'prises ,ajdrill-hea'def an erodiblematerial rigidly mounted ion-a shank and madeeccentric'thereto. The *drill head 'nixayhave either a circular circumference or an eccentric circumference and -has' at least three grinding teeth of material'that is'hafder tharrthe head setapproxirnately' radially in its face, the outer ends of the teeth-being spaced differently frornthe axis and substantially flush with the side ofthe head. V

When the drill is rotated, the'head wabbles slightly and actsas aneceentric-within'the hole, so that the grinding -teeth exertboth-a rotary and a sideways-abrading action. Preferably the face of the-head has an annular recess .or .core barrel? located slightlyeccentric with the axis .of rotationof the shaft. The core around whichthe teethgrindmay .be saved, or if preferred, broken out as drilling proceeds and ground out with the rest ofthe rock When the drill is to be employed to cut and conserve the core, the core barrel or hole in the face is formed concentrically with the axis of rotation ofthe shank and of circular circumference. However, in many cases it is desirable to employ the bit while breaking up and removing the core. In such cases the core barrel is set eccentrically' \vith respect to the axis of rotation of the shank and in a preferred form a least one of'the grinding 'menibers'is permitted to project slightly into the core barrel so that it provides a break out to aid in disintegrating the core.

The'grinding teeth may-be set'in the head (which prefera'bly is-oftoolsteel) by welding, brazing or the like. The term welded is used throughout'the specification "and claims as including-welded, brazed, soldered and any equivalent fastening.

Immediately above the bit proper, the apparatus should be-provided with an exterior helical thread or auger to removecuttings-from the neighborhood of the grinding face. Thus the shank of the bit may be constructed after the fashion of a .carpenters auger. In the larger size bits apreferred construction is to provide the shank at the end uponv which thehead is mounted with an enlarged barrel around which the helical threads. are formed so thatthe locus of rotation of the threads will approximatethe'diameter of the hole being bored. In any case the outside cross section of the anger or helical thread should correspond approximately to that of the drill "easily and do not tend to stick in the'hole, perhaps such Patented June 4, 1957 head i, e. the two should have approximately the same diameter.

The face of the drill head should be fiat and perpendicular to the axis of rotation, and the several grinding 'members should project from it in difiering amounts.

Thus the first grinding member or tooth may project a small amount, the second slightly more and the third still more. "in operation, the bit is rotated and pressed against the object to be drilled. The eccentric disposition of thegrinding teeth causes thehead of the drill to tary grinding action and greatly improves the drilling efficiency.

In another embodiment of the invention as hereinafter more fully described the'bit' head is provided with-a flat surface on its outer Wall adjacent to and'leading-each grinding memberhavingin mindthe'direction of rotation of the drill head. The provisionof the flat faces onthe otherwise curvilinear sides of the'head serve to accentuate and quicken the oscillatory motion of'the bit head within the hole.

"The.grindinginembers set in the face of the drill'head. maybe made of diamonds,"but for most purp o'ses such. expensive media are notrne'ces'sary and cemented carbide compositions that' arestrongly abrasion -resistantare prefe'rred. I have found that cemented tungsten carbides, "including at "leastsornef of the tungsten-titanium. carbides,

are preferable. It is customary to form strong, hard,

"abrasion-resistant members from such tun'gstn-titanium 30- carbides: employing cobalt or-other metals as a bi'nderwith or without 'carb'onized'tungsten. l-prefer to employ teeth which are roughly parallelepipeds and to setfth'em' at an obtuseangle-lathe face of thebit, again' havingfin'mind the direction of rotation-of the bit. I have foundthati the grinding or contacting edge of the'teeth" maybedisposed parallel to the face "of the'he'ad or'angularlyvvithrespect thereto in either direction; Thus foryparticular' purposes, as hereinafter describedfl have found that improved results are obtained by setting theteeth sonar the outeredg'es: thereof project fartherfrom the face of thehead member than the inner edges thereof.

Converselyl have found that for other purposes'im- =proved results 'are obtained-Whenthe teeth'are set with the inner edges thereof projecting a' greater distance from the'face of'the he'ad-member than the'outer e'dges thereof. For best results, as describedin-theaforementioned ap plication, the exposed long edge of the toothshould be 's'etparallelto a radius drawn from the "axis of rotation but; slightlyin advance of-this radius and'in the direction of rotation --of thebit. Bits'so' constructed operate more a the following detailed description thereof taken in conjunction with the accompanying'drawings in which: 7

Fig. 1 isa plan view of one form of my bit wherein fiat surfaces are cut in the sides of the head member;

Fig. 2 is an elevation of a bit such asthie bit 1 showing a modification in the helical thread formed in the barrel of the shank; p p g p Fig. 3 is view taken onthe line 3-3 of Fig. 2; r Fig. 4 is a plan view of an embodiment of the bit wherein the teeth members are elevated towardsthe centerofthebit; r V

Fig. 5 is an elevationof' the head member shownin Fig. 4; r

Fig. 6 is an elevation of the headniember' of a bit in Fig. 11 is a sectional elevation taken on the line 1111 of Fig. 10.

Referring to Figs. 1 and 2 the bit of the invention comprises a head 10, mounted integrally on a cylindrical shank portion 11 which is rotatable around an axis 12. The face of the head is fiat and is disposed perpendicularly to the axis 12 and is provided with a cylindrical recess or core barrel 13, the axis 12A of which is, in the embodiment shown, concentric with the axis 12 of the shank 11.

Set in the face of the head are three radial grinding teeth 14, and 16. The inner edges of three grinding members are spaced equidistant from the axis and substantially flush with the Wall of the core barrel. In this regard the teeth may project beyond the sides of the head a slight distance say on the order of to of an inch, but it is preferable to insure that the teeth do not fall short of reaching the edge of the head. Thus if the teeth 14, 15 and 16 are not flush it is at least desirable that they project beyond the side of the head 10 than fail to reach the side of the 'head 10.

As shown in Fig. 1 the preferred direction of rotation of the bit is counter-clockwise. The first tooth 14 is relatively short; the next tooth 15 being longer (say by of an inch), and the tooth 16 being still longer (say by ,4 of an inch). All extend approximately radially from the edge of the core barrel 13. The head 10 is so shaped that the several ends of the cutting members are substantially flush with the side thereof, giving a noncircular form to the face. Thus the head in the embodiment here shown is in the shape of a disc of eccentric external circumference.

In the bit as shown in Figs. 1 and 2 the side of the head 10 is further modified by the provision of the flat surfaces 18, 19 and 20 formed thereon adjacent to and leading the teeth 14, 15 and 16 respectively. As hereinbefore stated the effect of forming these fiat surfaces on the side of the head in front of the teeth is to accentuate the oscillatory action of the head and to thereby improve the grinding efiiciency of the teeth. This is a characteristic which is greatly to be desired inasmuch as the primary function of the bit of the invention is to provide a grinding rather than a cutting action.

The three grinding members 14, 15 and 16 are in the shape of paralllelepipeds set angularly in the face of the head 10 as may be clearly seen in Fig. 2 in the case of the grinding member 16. Thus the grinding member 16 inclines backwardly so that it presents its angular outer edge at an obtuse angle (say 120") in the direction of rotation of the bit.

. A short tooth 14 projects further from the face of the head than does the somewhat longer tooth 15, and this in turn projects further from the face than the longest tooth 16.

In the bit of Figs. 1 and 2 the shank 11 is provided with a barrel 22 upon which is formed'the helical thread 23. I have found that acme thread as shown, is, for this purpose, superior to screw thread which has a disadvantage of sloping outwardly thereby tending to force the cut- 7 tings away from the thread.

I have further found that improved results may be obtained in the disposal of the cuttings by providing in the helical thread 23 a groove or a number of grooves such as the groove 25. A groove 25 may be considered either as a longitudinal groove parallel to the axis of rotation of the shank or as a break in the thread 23 forming a continuous channel.

'Fig. 3 shows the three grooves'25, 26 and 27 in the threading 23 as related to the shank 11 and the barrel 22.

. 4 If the head 10 is approximately the same size as the shank 11 the barrel 22 may be eliminated and the threading 23 formed directly upon the shank 11. Thus Whether or not the barrel 22 is employed depends primarily upon the relative sizes of the head and shank.

As above mentioned certain types of drilling are facilitated by mounting the teeth so that the exposed grinding edge is not parallel to the face of the head. Thus in Figs. 4 and 5 there is shown a plan view and an elevation view respectively of the head 10 wherein the teeth 30, 31 and 32 project farther from the face of the head on inner ends thereof and slope so that the outer ends thereof are closer to the face of the head. This type of bit is particularly adapted to use in the drilling of very hard material wherein difiiculty may be normally encountered in starting the hole. I have found that the tapered grinding members 30, 31 and 32 facilitate the starting operation.

Conversely certain advantages are obtained in particular types of operation when the teeth are slanted in the opposite direction. Such type of construction is shown in the elevation view of Fig. 6 wherein the teeth 34, 35 and 36 are mounted in the face of the head 10 so that the outer edges thereof project farther from the face than do the inner edges. A bit of this nature finds particular application when it is desired to obtain a core inasmuch as it. has been found that the grinding members when sloped in this direction tend to preserve a more perfect core.

The bit shown in Fig. 6 is further provided with a tapered bore 40 projecting from the core barrel 42 through the barrel 22 of the shank. This type of construction is described in detail with relation to Figs. 7, 8 and 9 and is shown here to illustrate an additional function of the a sloping grinding members 34, 35 and 36.. As hereinafter described, the tapered bore 30 is used to aid in the ejection of material from the bore hole and I have found that this type of operation is aided by sloping the teeth in the direction as shown in Fig. 6 by virtue of the fact that the material to be discharged is channeled towards the center of the bit. Thus the use of grinding members tapering towards the center of the head member has been found to be advantageous either in obtaining a core in which case the core barrel is drilled concentrically to the axis of rotation of the shank, or in the disposal of cuttings when combined with a tapered bore such as the bore 40. In this latter case, the core barrel 42 is preferably drilled eccentrically with respect to the axis of rotation of the shank although the tapered bore.40 may be concentric thereto. Further improved results are obtained in this latter instance if one of the grinding members is allowed to project a short distance within the core barrel so as to aid in breaking up any core which may tend to form therein. Thus in Fig. 6 the grinding member 36 is shown projecting into the core barrel to accomplish this purpose. 7

A further embodiment of the invention is shown in Figs. 7, 8 and 9 which is particularly suited to the removal of cuttings from the hole as the drilling proceeds. Fig. 7

- is a plan view of such a bit;

Fig. 8 is a sectional elevation taken on the line 88 of Fig. 7; and

7 grinding members 56, 57 and 58 exposed in, the'face of the head member 50 and projecting from the core barrel 60 to the outer edge of the head 50. The barrel 54 is similarly provided with means on the exterior thereof to discharge the cuttings out of the hole, such as for holes 64, 65, .66 and example the helical thread 61 which issimilar tothe acme threads 23 shown in Fig.2.

A tapered bore 62 is formed in the barrel 54 and-pro- --jects from the core barrel 60 substantially all the way through the core barrel-54-. Although inthe preferred form of this type of bitthecore barrel 60 is formed eccentrically with the axis of rotation of the shank 52, the tapered bore 62 is conveniently: formed concentrically therewith. As clearly seen in Fig.8 the tapered bore 62 tapers in the direction of the shank 52 so that it is larger in cross section at its terminus within the barrel 54 than at the point of entry at the core barrel 60. This taper is provided so as to, prevent jamming of the'cut tings as they are forcednp the tapered bore 62.

The meansshown in Figs.,8-and 9' for discharging the cuttings? from the taperedbore 62 comprises the tapered 67 projecting from the end of the tapered bore 62 out the chamfered face 54a of the barrel 54. These holes 64, 65 etc., are likewise preferably tapered beinglargerin cross section at the point of exit from the barrel 5.4 th'anat the point ofcontact with the tapered bore 62 for the same reason that the bore 62 is preferably tapered. Both Figs. 8 and 9 represent a preferred form of this type of bit and it is to be understood that means may be provided anywhere along the barrel 54 for discharging the cuttings passing through the tapered bore 62. Likewise it is not necessary that the end of the barrel 54 be chamfered as shown at 54:: although this type of construction permits the discharge of the cuttings from the tapered bore 62 at the end of the barrel 54 and at the same time does not interfere with the mechanical strength of the union between the shank 52 and the barrel 54.

An additional modification of the invention is also shown in Fig. 8 and comprises the inclusion of a thin copper shim such as the shim 70 beneath each of the grinding members 56, 57 and 58 which shim tends to act as a shock absorber reducing the effect of impact on the grinding members. The shim is conveniently formed so as to fit the bottom of the grinding members as is illustrated by the shim 72 disposed beneath the grinding member 56 in Fig. 8.

As hereinbefore mentioned when employing this type of bit, it may be desirable to taper the teeth inwardly towards the core barrel as shown in Fig. 6. However, the various embodiments shown in Figs. 1 to 9 are capable of combination in any desired fashion to obtain the best results in any particular case. Thus the head 50 in the bit as shown in Figs. 7, 8 and 9 may be provided with flat surfaces such as the surfaces 18, 19 and 20 in Fig. 1. Further, the thread 61 in Ithe bit of Fig. 8 may be provided with the grooves such as the grooves 25, 26 or 27 in the Fig. 2. The combination of the longitudinal groove on the outer surface of the bit body, as in the embodiment of Fig. 2, and the longitudinal bore and lateral outlet therefrom, as disclosed in Fig. 8, is illustrated in the bit shown in elevation in Fig. 10 and in sectional elevation in Fig. 11, the latter figure being taken on the line 11-11 of Fig. 10. A bit 80 illustrated in these figures includes a cylindrical body 81 to which a shank 82 is attached. The body 81 is provided with a bore 84 forming an annular flat face 81a at the end of the body opposite shank 82. A plurality of carbide cutting teeth 85 are set in approximately equal angularly spaced radii in the annular end face 81:: and with at least one of the teeth extending radially inwardly of the annular end face. The body 81 is provided with a helical groove 87 extending substantially from end to end thereof and providing means for carrying cuttings away from the cutting face. An opening 38 in the body wall gives access to the bore 84 and provides passageway for discharge of material channeled upwardly in the bore 84 during the drilling operation. A groove 90 similar to the groove 25 in the embodiment of Fig. 2 is formed on the outer surface of the body intersecting thread 87. The groove 6" serves the same function as thecorresponding groove 25 illustrated in Fig.2 in facilitating the channelingof the cuttings,developed'duringthe drilling operation, up-

wardly of the .body. Thus the various improvements shown herein in thebit as described inlthe aforementioned co-pending application may. be combined in the samebit or may be usedindividually in bits of. difierentdesign depending uponthe circumstances underwhich the bit is to be employed.

-Many modifications in the bit of the invention may occur to those skilled in. the art from the foregoing description and illustration without departing from the scope of-the invention as described and claimed;

.the body, the body having. a longitudinal-bore extending substantially the .lengththereof and. communicating with its annular end face, the bore being tapered so that its cross-sectional area increases with increasing distances from the annular end face, the body also having a plurality of openings which extend from the chamfered end face to the longitudinal bore.

2. The apparatus of claim 1, wherein each of the openings of said plurality of openings =is tapered toward the axis of the body.

3. The apparatus of claim 1, wherein the body has a cylindrical bore located intermediate the tapered bore and the annular end face of the body.

4. The apparatus of claim 3, wherein the cylindrical bore is eccentrically located with respect to the longitudinal axis of the body.

5. The apparatus of claim 1, wherein the teeth are tapered toward the longitudinal axis of the body so that the outer edges of the Iteeth protrude farther from the annular face of the bit than the inner edges of the teeth.

6. A bit for drilling concrete comprising an elongated cylindrical body having a longitudinal bore therein and an annular transverse planar face at one end of the body through which the bore opens, a plurality of teeth welded in approximately radially disposed grooves in the annular end face of the body and projecting axially beyond the annular end face with at least one tooth projecting radially into the bore of the body to inhibit formation of a discrete core, a shank extending from the other end of the body, and a spiral thread located on the outer surface of the body, the bore in the body being tapered so that its cross-sectional area increases with increasing distances from the annular end face, the body also having at least one opening in the wall thereof communicating with the bore and providing an outlet for disintegrated material released into the bore while drilling.

7. A rotary bit for drilling concrete comprising an elongated cylindrical body having a longitudinal bore therein and an annular transverse planar face at one end of the body through which the bore opens, a plurality of carbide cutting teeth welded in approximately radially disposed grooves in the annular end face of the body and projecting axially beyond the annular end face with at least one tooth projecting radially into the bore of the body to disintegrate material lying inwardly of the end face during drilling, a shank extending from the other end of the body, a spiral thread located on the outer surface of the body, and the body having at least one opening in a wall thereof communicating with the bore providing outlet for the disintegrated material released into the bore during the drilling operation.

8. A rotary bit for drilling concrete comprising an elongated cylindrical body having a longitudinal bore therein and an annular transverse planar face at one end of the body through which the bore opens, said face of the body having a plurality of substantially radially disposed 7 7 v grooves therein, a separate carbide tooth Welded in each groove and projecting axially from the end face and at least one tooth projecting radially into the bore of the body, the teeth serving to fill the grooves so that the planar face is interrupted substantially only by tooth projection, a shank extending longitudinally from the other end of the body, a spiral thread located on the outer surface of the body with the threads being of substantially the same outside diameter as the outer circumference of the annular end face, and the body having an opening 'in a Wall thereof communicating with the bore.

9. A rotary bit for drilling concrete and other hard abrasive materials, comprising an elongated cylindrical body having a longitudinal bore therein and an annular transverse planar face at one end of the body through which the bore opens, said face of the body having a plurality of substantially radially disposed grooves therein, a separate carbide tooth Welded in and substantially filling each groove and projecting axially from the end face, at least one of said teeth extending into the bore of the body to disintegrate material lying inwardly of the end face 7 References Cited in the file of this patent UNITED STATES PATENTS Tilden Aug. 26, 1952 76,188 Heath Mar. 31, 1868 1,271,396 Walker July 2, 1918 1,512,841 Gamble Oct. 21, 1924 1,544,167 Nightingale June 30, 1925 1,805,899 Wright May 19, 1931 1,846,177 Bascom et al Feb. 23, 1932 2,188,631 Kraus Jan. 30, 1940 2,524,570 Phipps Oct. 3, 1950 

